In many industries, a flow of air is used for transporting various types of object, both objects of value and also all kinds of waste and scrap. The flow of air is obtained by flowing or by suction or by a combination of these two techniques. This is done by means of aspirators, or injectors, or equivlent devices, in which a suitably formed air inlet (or more generally gas inlet) induces a flow of air (or gas) containing the objects to be transported. At the end of the installation (or more generally on the flow path), there is naturally a need for separating said transported objects from the air (or gas) transporting them. Devices for providing this separation are called separators.
This separation function must take account of the shape of the transported objects, of their density, of their concentration in the air flow, and of their speed of travel.
It is also necessary to ensure that separation is as thorough as possible and in particular to prevent the objects from being accompanied by residual air which could disturb subsequent operations to be performed on the objects.
To perform this type of separation, proposals have been made for devices called cyclones and for devices called separators. These two types of device operate on different principles: for cyclones, the transported objects are thrust by the centrifugal force of the air against the outer wall of the device with the air leaving via the top middle portion of the device; whereas in separators, the objects are recovered on a grid or perforated plate and the air which passes through the grid generally leaves the device tangentially.
As mentioned above, these two types of device operate on different principles, and consequently they generally have different applications.
Devices of the separator type are more generally used for separating transported objects which, together with the air serving to transport them, occupy a certain volume, with separator devices, other things being equal, having the advantage of occupying considerably smaller volumes than would be required for the corresponding cyclones.
Numerous proposals have already been made for a wide variety of separators including separation grids which are plane or cylindrical. One separator now on the market is constituted by a cylindrical grid which is open at its top and bottom ends and which is surrounded by a solid cylindrical envelope leaving an empty space between tthe envelope and the grid. The air (or gas) entraining the transported objects arrives at the top of the grid travelling tangentially thereto. The air passing through the grid is recovered in an exhaust disposed tangentially relative to said envelope and preferably located at the bottom thereof. The top of the grid and envelope assembly is closed by a cover and the bottom of the envelope is constituted by a truncated conical portion connected directly to the grid so as to collect the objects that have been transported and separated from the air by said grid. Said truncated cone which may optionally be connected to an airtight enclosure (when suction is used) is designed in such a way that it sets up a head loss so that the air which leaves said truncated cone together with the "concentrated" objects is at a pressure which is zero or very close to zero, or is at a pressure that is compatible with the pressure of the suction device.
One such separator is shown diagrammatically in elevation in FIG. 1 and in section on II--II in FIG. 2.
These figures show:
the cylindrical grid 1; PA0 the outer envelope 2; PA0 the high tangential inlet 3 for the mixture of air and transported objects; PA0 the air outlet 4; and PA0 the truncated cone 5 via which the objects are removed after being separated from the air.
The present invention relates to a separator which is an improvement over the cylindrical separators described briefly above.